The main message of the given excerpt of White Fang:
The whole passage depicts the phrase "Love begets love".
In the passage given, both Billy and Henry after all the toiling short-lived panic return along with their dogs. Bill feels that it would be fine if the dogs leave them alone.
The message here is every living-being in this universe have their own instincts. Likewise, human tends to defend themselves and their possessions. When someone or something is causing a discomfort, they tend to get rid of their inconvenience by one or the other feasible ways.
When one being shows love or compassion to the other in turn they receive the same love. The whole story of White Fang tale states this as a bottom line.